Linux设备驱动程序学习-Linux设备模型（总线、设备、驱动程序和类）

struct bus_type {

const char        * name;/*总线类型名称*/

struct module        * owner;/*指向模块的指针(如果有), 此模块负责操作这个总线*/

struct kset        subsys;/*与该总线相关的子系统*/

struct kset        drivers;/*总线驱动程序的kset*/

struct kset        devices;/* 挂在该总线的所有设备的kset*/

struct klist        klist_devices;/*与该总线相关的驱动程序链表*/

struct klist        klist_drivers;/*挂接在该总线的设备链表*/

struct blocking_notifier_head bus_notifier;

struct bus_attribute    * bus_attrs; /*总线属性*/

struct device_attribute * dev_attrs; /*设备属性,指向为每个加入总线的设备建立的默认属性链表*/

struct driver_attribute * drv_attrs; /*驱动程序属性*/

struct bus_attribute drivers_autoprobe_attr;/*驱动自动探测属性*/

struct bus_attribute drivers_probe_attr;/*驱动探测属性*/

int        (*match)(struct device * dev, struct device_driver * drv);

int        (*uevent)(struct device *dev, char **envp,

int num_envp, char *buffer, int buffer_size);

int        (*probe)(struct device * dev);

int        (*remove)(struct device * dev);

void        (*shutdown)(struct device * dev);

int (*suspend)(struct device * dev, pm_message_t
state);

int (*suspend_late)(struct device * dev, pm_message_t
state);

int (*resume_early)(struct device * dev);

nt (*resume)(struct device * dev);

/*处理热插拔、电源管理、探测和移除等事件的方法*/

unsigned int drivers_autoprobe:1;

};

struct bus_type ldd_bus_type = {

.name = "ldd",

.match = ldd_match,

.uevent = ldd_uevent,

};

int bus_register(struct bus_type * bus)

ret = bus_register(&ldd_bus_type);

if (ret)

return ret;

void bus_unregister(struct bus_type *bus);

int (*match)(struct device * dev, struct device_driver * drv);

/*当一个新设备或者驱动被添加到这个总线时，这个方法会被调用一次或多次，若指定的驱动程序能够处理指定的设备，则返回非零值。必须在总线层使用这个函数, 因为那里存在正确的逻辑，核心内核不知道如何为每个总线类型匹配设备和驱动程序*/

int (*uevent)(struct device *dev, char **envp, int num_envp, char *buffer, intbuffer_size);

/*在为用户空间产生热插拔事件之前，这个方法允许总线添加环境变量（参数和 kset 的uevent方法相同）*/

static int ldd_match(struct device *dev, struct device_driver *driver)

{

return !strncmp(dev->bus_id, driver->name, strlen(driver->name));

}/*仅简单比较驱动和设备的名字*/

/*当涉及实际硬件时, match 函数常常对设备提供的硬件 ID 和驱动所支持的 ID 做比较*/

static int ldd_uevent(struct device *dev, char **envp, int num_envp, char *buffer,int buffer_size)

{

envp[0] = buffer;

if (snprintf(buffer, buffer_size, "LDDBUS_VERSION=%s",

Version) >= buffer_size)

return -ENOMEM;

envp[1] = NULL;

return 0;

}/*在环境变量中加入 lddbus 源码的当前版本号*/

int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data, int(*fn)(struct device *, void *));

int bus_for_each_drv(struct bus_type *bus, struct device_driver *start, void *data,int (*fn)(struct device_driver *, void *));

/*这两个函数迭代总线上的每个设备或驱动程序, 将关联的 device 或 device_driver 传递给 fn, 同时传递 data 值。若 start 为 NULL, 则从第一个设备开始; 否则从 start 之后的第一个设备开始。若 fn 返回非零值, 迭代停止并且那个值从 bus_for_each_dev 或bus_for_each_drv 返回。*/

struct bus_attribute {

struct attribute    attr;

ssize_t (*show)(struct bus_type *, char * buf);

ssize_t (*store)(struct bus_type *, const char * buf, size_t count);

};

BUS_ATTR(_name,_mode,_show,_store)/*这个宏声明一个结构,
将 bus_attr_ 作为给定 _name 的前缀来创建总线的真正名称*/

/*总线的属性必须显式调用 bus_create_file 来创建:*/

int bus_create_file(struct bus_type *bus, struct bus_attribute *attr);

/*删除总线的属性调用:*/

void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr);

static ssize_t show_bus_version(struct bus_type *bus, char *buf)

{

return snprintf(buf, PAGE_SIZE, "%s/n", Version);

}

static BUS_ATTR(version, S_IRUGO, show_bus_version, NULL);

/*在模块加载时创建属性文件:*/

if (bus_create_file(&ldd_bus_type, &bus_attr_version))

printk(KERN_NOTICE "Unable to create version attribute/n");

/*这个调用创建一个包含 lddbus 代码的版本号的属性文件(/sys/bus/ldd/version)*/

struct device {

struct klist        klist_children;

struct klist_node    knode_parent;   /* node in sibling list */

struct klist_node    knode_driver;

struct klist_node    knode_bus;

struct device        *parent;/* 设备的 "父" 设备，该设备所属的设备，通常一个父设备是某种总线或者主控制器. 如果 parent 是 NULL, 则该设备是顶层设备，较少见
*/

struct kobject kobj;/*代表该设备并将其连接到结构体系中的 kobject； 注意：作为通用的规则, device->kobj->parent 应等于 device->parent->kobj*/

char    bus_id[BUS_ID_SIZE];/*在总线上唯一标识该设备的字符串;例如: PCI 设备使用标准的
PCI ID 格式, 包含:域, 总线, 设备, 和功能号.*/

struct device_type    *type;

unsigned        is_registered:1;

unsigned        uevent_suppress:1;

struct device_attribute uevent_attr;

struct device_attribute *devt_attr;

struct semaphore    sem;  /* semaphore to synchronize calls to its driver. */

struct bus_type    * bus;     /*标识该设备连接在何种类型的总线上*/

struct device_driver *driver;    /*管理该设备的驱动程序*/

void        *driver_data;    /*该设备驱动使用的私有数据成员*/

void        *platform_data;    /* Platform specific data, device core doesn't touch it */

struct dev_pm_info    power;

#ifdef CONFIG_NUMA

int        numa_node;   /* NUMA node this device is close to */

#endif

u64        *dma_mask;    /* dma mask (if dma'able device) */

u64        coherent_dma_mask;/* Like dma_mask, but for

alloc_coherent mappings as

not all hardware supports

64 bit addresses for consistent

allocations such descriptors. */

struct list_head    dma_pools;    /* dma pools (if dma'ble) */

struct dma_coherent_mem    *dma_mem; /* internal for coherent mem override */

/* arch specific additions */

struct dev_archdata    archdata;

spinlock_t        devres_lock;

struct list_head    devres_head;

/* class_device migration path */

struct list_head    node;

struct class        *class;

dev_t          devt;       /* dev_t, creates the sysfs "dev" */

struct attribute_group    **groups;    /* optional groups
*/

void    (*release)(struct device * dev);/*当这个设备的最后引用被删除时，内核调用该方法;
它从被嵌入的 kobject 的 release 方法中调用。所有注册到核心的设备结构必须有一个 release 方法, 否则内核将打印错误信息*/

};

/*在注册 struct device 前，最少要设置parent, bus_id, bus, 和 release 成员*/

int device_register(struct device *dev);

void device_unregister(struct device *dev);

static void ldd_bus_release(struct device *dev)

{

printk(KERN_DEBUG "lddbus release/n");

}

struct device ldd_bus = {

.bus_id = "ldd0",

.release = ldd_bus_release

}; /*这是顶层总线，parent 和 bus 成员为 NULL*/

/*作为第一个(并且唯一)总线, 它的名字为 ldd0，这个总线设备的注册代码如下:*/

ret = device_register(&ldd_bus);

if (ret)

printk(KERN_NOTICE "Unable to register ldd0/n");

/*一旦调用完成, 新总线会在 sysfs 中 /sys/devices 下显示，任何挂到这个总线的设备会在 /sys/devices/ldd0 下显示*/

/* interface for exporting device attributes 这个结构体和《LDD3》中的不同，已经被更新过了，请特别注意！*/

struct device_attribute {

struct attribute attr;

ssize_t (*show)(struct device *dev, struct
device_attribute *attr,char *buf);

ssize_t (*store)(struct device *dev, struct
device_attribute *attr, const char*buf, size_t
count);

};

/*设备属性结构可在编译时建立, 使用以下宏:*/

DEVICE_ATTR(_name,_mode,_show,_store);

/*这个宏声明一个结构, 将 dev_attr_ 作为给定 _name 的前缀来命名设备属性

/*属性文件的实际处理使用以下函数:*/

int device_create_file(struct device *device,    struct device_attribute * entry);

void device_remove_file(struct device * dev, struct device_attribute * attr);

struct ldd_device {

char *name;

struct ldd_driver *driver;

struct device dev;

};

#define to_ldd_device(dev) container_of(dev, struct ldd_device, dev);

/*

* LDD devices.

*/

/*

* For now, no references to LDDbus devices go out which are not

* tracked via the module reference count, so we use a no-op

* release function.

*/

static void ldd_dev_release(struct device *dev)

{ }

int register_ldd_device(struct ldd_device *ldddev)

{

ldddev->dev.bus = &ldd_bus_type;

ldddev->dev.parent = &ldd_bus;

ldddev->dev.release = ldd_dev_release;

strncpy(ldddev->dev.bus_id, ldddev->name, BUS_ID_SIZE);

return device_register(&ldddev->dev);

}

EXPORT_SYMBOL(register_ldd_device);

void unregister_ldd_device(struct ldd_device *ldddev)

{

device_unregister(&ldddev->dev);

}

EXPORT_SYMBOL(unregister_ldd_device);

static ssize_t sculld_show_dev(struct device *ddev,

struct
device_attribute *attr,

char *buf)

{

struct sculld_dev *dev = ddev->driver_data;

return print_dev_t(buf, dev->cdev.dev);

}

static DEVICE_ATTR(dev, S_IRUGO, sculld_show_dev, NULL);

/*接着, 在初始化时间, 设备被注册, 并且 dev 属性通过下面的函数被创建:*/

static void sculld_register_dev(struct sculld_dev *dev, int index)

{

sprintf(dev->devname, "sculld%d", index);

dev->ldev.name = dev->devname;

dev->ldev.driver = &sculld_driver;

dev->ldev.dev.driver_data = dev;

register_ldd_device(&dev->ldev);

if (device_create_file(&dev->ldev.dev, &dev_attr_dev))

printk( "Unable to create dev attribute ! /n");

} /*注意：程序使用 driver_data 成员来存储指向我们自己的内部的设备结构的指针。请检查

device_create_file

的返回值，否则编译时会有警告。*/

/*定义在<linux/device.h>*/

struct device_driver {

const char        * name;/*驱动程序的名字( 在 sysfs 中出现 )*/

struct bus_type        * bus;/*驱动程序所操作的总线类型*/

struct kobject        kobj;/*内嵌的kobject对象*/

struct klist        klist_devices;/*当前驱动程序能操作的设备链表*/

struct klist_node    knode_bus;

struct module        * owner;

const char         * mod_name;    /* used for built-in modules
*/

struct module_kobject    * mkobj;

int    (*probe)    (struct device * dev);/*查询一个特定设备是否存在及驱动是否可以使用它的函数*/

int    (*remove)    (struct device * dev);/*将设备从系统中删除*/

void    (*shutdown)    (struct device * dev);/*关闭设备*/

int    (*suspend)    (struct device * dev, pm_message_t
state);

int    (*resume)    (struct device * dev);

};

/*注册device_driver 结构的函数是:*/

int driver_register(struct device_driver *drv);

void driver_unregister(struct device_driver *drv);

/*driver的属性结构在:*/

struct driver_attribute {

struct attribute attr;

ssize_t (*show)(struct device_driver *drv, char *buf);

ssize_t (*store)(struct device_driver *drv, const char *buf, size_t count);

};

DRIVER_ATTR(_name,_mode,_show,_store)

/*属性文件创建的方法:*/

int driver_create_file(struct device_driver * drv, struct driver_attribute * attr);

void driver_remove_file(struct device_driver * drv, struct driver_attribute *attr);

/*bus_type 结构含有一个成员( drv_attrs ) 指向一组为属于该总线的所有设备创建的默认属性*/

struct ldd_driver {

char *version;

struct module *module;

struct device_driver driver;

struct driver_attribute version_attr;

};

#define to_ldd_driver(drv) container_of(drv, struct ldd_driver, driver);

/*

* Crude driver interface.

*/

static ssize_t show_version(struct device_driver *driver, char *buf)

{

struct ldd_driver *ldriver = to_ldd_driver(driver);

sprintf(buf, "%s/n", ldriver->version);

return strlen(buf);

}

int register_ldd_driver(struct ldd_driver *driver)

{

int ret;

driver->driver.bus = &ldd_bus_type;

ret = driver_register(&driver->driver);/*注册底层的
device_driver 结构到核心*/

if (ret)

return ret;

driver->version_attr.attr.name = "version";/*
driver_attribute 结构必须手工填充*/

driver->version_attr.attr.owner = driver->module;/*注意:设定
version 属性的拥有者为驱动模块, 不是 lddbus 模块！因为 show_version 函数是使用驱动模块所创建的 ldd_driver 结构，若 ldd_driver 结构在一个用户空间进程试图读取版本号时已经注销，就会出错*/

driver->version_attr.attr.mode = S_IRUGO;

driver->version_attr.show = show_version;

driver->version_attr.store = NULL;

return driver_create_file(&driver->driver, &driver->version_attr);/*建立版本属性，因为这个属性在运行时被创建，所以不能使用
DRIVER_ATTR 宏*/

}

void unregister_ldd_driver(struct ldd_driver *driver)

{

driver_unregister(&driver->driver);

}

EXPORT_SYMBOL(register_ldd_driver);

EXPORT_SYMBOL(unregister_ldd_driver);

/* Device model stuff */

static struct ldd_driver sculld_driver = {

.version = "$Revision: 1.21 $",

.module = THIS_MODULE,

.driver = {

.name = "sculld",

},

};/*只要一个简单的 register_ldd_driver 调用就可添加它到系统中。一旦完成初始化, 驱动信息可在 sysfs 中显示*/

/*

* device classes

*/

struct class {

const char        * name;/*每个类需要一个唯一的名字, 它将显示在 /sys/class
中*/

struct module        * owner;

struct kset        subsys;

struct list_head    children;

struct list_head    devices;

struct list_head    interfaces;

struct kset        class_dirs;

struct semaphore    sem;    /* locks both the children and interfaces lists */

struct class_attribute        * class_attrs;/* 指向类属性的指针（以NULL结尾） */

struct class_device_attribute    * class_dev_attrs;/* 指向类中每个设备的一组默认属性的指针 */

struct device_attribute        * dev_attrs;

int    (*uevent)(struct class_device *dev, char **envp,

int num_envp, char *buffer, int buffer_size);/*
类热插拔产生时添加环境变量的函数 */

int    (*dev_uevent)(struct device *dev, char **envp, int num_envp,

char *buffer, int buffer_size);/*
类中的设备热插拔时添加环境变量的函数 */

void    (*release)(struct class_device *dev);/*
把设备从类中删除的函数 */

void    (*class_release)(struct class *class);/*
删除类本身的函数 */

void    (*dev_release)(struct device *dev);

int    (*suspend)(struct device *, pm_message_t
state);

int    (*resume)(struct device *);

};

/*类注册函数:*/

int class_register(struct class *cls);

void class_unregister(struct class *cls);

/*类属性的接口:*/

struct class_attribute {

struct attribute attr;

ssize_t (*show)(struct class *cls, char *buf);

ssize_t (*store)(struct class *cls, const char *buf, size_t count);

};

CLASS_ATTR(_name,_mode,_show,_store);

int class_create_file(struct class *cls, const struct class_attribute *attr);

void class_remove_file(struct class *cls, const struct class_attribute *attr);

struct class_device {

struct list_head    node;/*for internal use by the driver core only*/

struct kobject        kobj;/*for internal use by the driver core only*/

struct class        * class;    /*
指向该设备所属的类，必须*/

dev_t            devt;        /* dev_t, creates the sysfs "dev" ，for internal use by the driver core only*/

struct class_device_attribute *devt_attr;/*for internal use by the driver core only*/

struct class_device_attribute uevent_attr;

struct device        * dev;        /* 指向此设备相关的 device 结构体，可选。若不为NULL，应是一个从类入口到/sys/devices 下相应入口的符号连接，以便用户空间查找设备入口*/

void            * class_data;    /* 私有数据指针 */

struct class_device    *parent;    /* parent of this child device, if there is one */

struct attribute_group ** groups;    /* optional groups */

void    (*release)(struct class_device *dev);

int    (*uevent)(struct class_device *dev, char **envp,

int num_envp, char *buffer, int buffer_size);

char    class_id[BUS_ID_SIZE];    /* 此类中的唯一的名字 */

};

/*类设备注册函数:*/

int class_device_register(struct class_device *cd);

void class_device_unregister(struct class_device *cd);

/*重命名一个已经注册的类设备入口:*/

int class_device_rename(struct class_device *cd, char *new_name);

/*类设备入口属性:*/

struct class_device_attribute {

struct attribute attr;

ssize_t (*show)(struct class_device *cls, char *buf);

ssize_t (*store)(struct class_device *cls, const char *buf,

size_t count);

};

CLASS_DEVICE_ATTR(_name, _mode, _show, _store);

/*创建和删除除struct class中设备默认属性外的属性*/

int class_device_create_file(struct class_device *cls, const structclass_device_attribute *attr);

void class_device_remove_file(struct class_device *cls, const structclass_device_attribute *attr);

struct class_interface {

struct list_head    node;

struct class        *class;/*
指向该接口所属的类*/

int (*add) (struct class_device *, struct class_interface *);

/*当一个类设备被加入到在 class_interface 结构中指定的类时, 将调用接口的 add 函数，进行一些设备需要的额外设置，通常是添加更多属性或其他的一些工作*/

void (*remove)    (struct class_device *, struct class_interface *);/*一个接口的功能是简单明了的.
当设备从类中删除, 将调用remove 方法来进行必要的清理*/

int (*add_dev)     (struct device *, struct class_interface *);

void (*remove_dev) (struct device *, struct class_interface *);

};

/*注册或注销接口的函数:*/

int class_interface_register(struct class_interface *class_intf);

void class_interface_unregister(struct class_interface *class_intf);

/*一个类可注册多个接口*/